- Patients being treated with drugs recognized as being strong inhibitors or inducers of the isoenzyme CYP3A at enrolment (rifabutin, rifampicin, clarithromycin, ketoconazole, itraconazole, voriconazole, ritonavir, telithromycin) continuously for at least 7 days during any time period in the last 2 weeks prior to enrolment